Carbonizing process



United States Patent 3,057,687 CARBONIZENG PROCESS Charles V. Mitchell, Shaker Heights, Ohio, assignor to Union Carbide Corporation, a corporation of New York No Drawing. Filed Feb. 8, 1961, Ser. No. 87,757 6 Claims. (Cl. 23-209.1)

This invention relates to a process for increasing the yield of carbon and graphite from selected aromatic compounds which normally do not produce appreciable quantities of carbon when coked at atmospheric pressure.

It is known that most lower molecular weight, polynuclear, aromatic compounds give little or no carbon when coked under non-oxidizing conditions at atmospheric pressure and temperatures above about 450 C.

This has been considered unfortunate from the standpoint that these compounds are easily purified and could constitute a source of high grade carbon and graphite for applications wherein high purity material is necessary.

The main object of this invention, then, is to provide means for increasing the yield of carbon and graphite from selected aromatic compounds.

This object has been attained in accord With the inverrtion which comprises mixing from 1 to 30 parts by weight of iodine with 100 parts by weight of aromatic j compound followed by coking of the mixture to form carbon.

The present invention is applicable to those aromatic compounds having a structure containing two to four fused rings and which are able to share electrons with iodine to form a complex therewith. Such compounds include anthracene, acenaphthene, acridine, 2-3 benzodiphenylene oxide, carbazole, chrysene, fluoranthene, indene, phenanthrene, pyrene, quinoline, 1,2-benzanthracene, triphenylene, 3,4-benzphenanthrene and alkyl derivatives of such compounds, such as methyl anthracene, ethyl anthracene, dimethyl anthracene and mixtures thereof. The process of the invention is also applicable to pctroleum oils which are known to contain mixtures of alkylated derivatives of aromatic compounds having the indicated fused ring structure. The additive of the invention will also increase the yield of carbon from bydrocarbons which give some carbon on coking, such as acenaphthylene and naphthacene. The coke prepared by the present process may contain small amounts of iodine.

Coking may be done on any scale in a manner similar to that illustrated in the following experiments. The compound is weighed out into a glass beaker or other suitable non-reactive container. The iodine is weighed out and added to the compound with thorough mixing. The glass beaker with its contents is placed inside a metal beaker. The beaker in turn is placed inside a protective double metal sagger which is packed with steel wool, charcoal, and sand to prevent oxidation of the sample. The temperature is increased slowly to a temperature somewhat below final coking temperature, held there for several hours, increased to final coking temperature and held there for a few hours. The preferred heating schedule used during coking is from about 10 to about 60 C. rise per hour to 390 C., a ten-hour hold period at 390 C., then a 60 C. rise per hour to 475 C. and a six-hour hold period at 475 C., followed by cooling and collection of the product.

Although the preferred range of amount of iodine is from about 10 to about 20 parts per hundred parts of organic compound, a broad range of 1-30 p.p.h. may be employed as desired. Experiments with as little as 1, 2

and 5 parts per hundred of iodine showed improvement in the coking yields of the compounds. Larger amounts were considerably more eitective.

The results of the addition of 10 or 20 parts per hundred (p.p.h.) of iodine on the coking value at atmospheric pressure after heating to about 475 C. of a number of aromatic hydrocarbons and compounds are shown in Table I. It should be noted that in most cases those compounds which ordinarily yield little or no coke became reasonably productive of coke with the addition of iodine. In addition, there has occurred an increase in the yield of coke from those compounds which originally gave some coke. The data presented, then, proves that iodine will bring about the formation of coke in most cases Where little or none was formed previously and will give an increased yield where coke was formed previously.

It has been observed that when larger samples are employed, the coke yields are somewhat higher presumably because of greater surface area contact between the aromatic hydrocarbon and the iodine, with a resultant better utilization of the additive. This effect may be observed with a certain compound, chrysene, as follows:

Vgith coking value after heating to 50475 C. with 10 p.p.h. iodine Chrysene sample weight, gm.

The degree of iodine retention was determined for coke produced from the following sources:

Iodine Content (Wt. Amount of Percent) of CokeAtter Compound Iodine Heating to- Ernpltilyed,

While the degree of iodine'retention varies with the compound, it is usually in the range of about 0.4 to about 5.0 percent.

The effect of iodine on the quality of graphite obtained from cokes prepared in the presence of iodine is shown in Table II. For this determination, raw cokes, obtained from the indicated compounds at 450 to 500 C. were calcined to 1000 C., then crushed and sized to make a coke flour which Was hot-mixed with coal tar pitch and formed into rods by extrusion. These rods were baked to 1000" C. and were then graphitized at 3000 C. The properties listed in Table 11 result from measurements made on the thus-prepared rods.

For purpose of comparison a range of physical properties displayed by 3000 C. graphitized articles prepared from petroleum coke obtained from various material and refinery sources also is shown in Table II. It can be seen that physical properties obtained with thefa'ddition of iodine to the aromatic hydrocarbons generally compare quite favorably with properties obtained with petroleum coke articles. Other ways of increasing the yield of carbon or coke from these same compounds exist, but these require the use of superatmospheric pressures, or of a dehydrogenating agent, such as sulfur. Pressure does not adversely affect coke quality, but sulfur generally does. f

Certain petroleum oils are known to contain varying amounts of alkylated derivatives of aromatic compounds having fused ring structures. Such oils were also subjected to the process of the invention.

The same data as above-presented in connection with single compounds, appears in Table III for petroleum oils to which iodine had been added prior to coking. Examination of this data ShOWs improvement in the coking value of the oil when iodine is added thereto. This improvement is not as marked as in the case of the single compounds, possibly because of dilution effects and other interfering factors.

Iodine appears to bring about this increased yield of carbon by forming a complex with the compound. This complex is stable enough to tie down the compound and prevent its loss by distillation or sublimation, yet reactive enough to cause the molecules to react with each .other and polymerize to form a more highly carbonaceous structure. Iodine does not seem to function as a de- 4 TABLE II Results of Rod Method Evaluation of Various Cokes CTE= Coeiiieient of Thermal Expansion (measured over the range of C. to 100 0.).

TABLE III Efiect of Iodine Additions on Yield and Quality of Coke From Various Types of Petroleum Charge Stocks [150-300 g. sample size] Percent Coke Yield Properties oi 3,000 C.

at Percent Graphite Iodine Improve- 1 wt 11 1 Addi' iii i s ifi T e o 1 ate a tive yie o pee e W p.p.h. coke A.D, Resist- CTE X 450 C. 1,000 C. (1,000G.) g./cm. ance 10' C.

u ohmcm.

Slurry Oil None 8.8 8. (0) 1. 54 869 4. 9

n (11.0) 2 (10.2) 2 (+27. 5) D0 l 12. 7 11. 8 1 (+47. 5) 1.51 853 7. 4

2 (14.0) 2 (13.0) 2 (+62. 5) DesulfurizedHeavy Catalytic Cycle Oil None 2.4 2.2 1.52 978 7.2 Do 10 6.4 1 5.9 l (+168) 1.48 955 7.5

1 Based on oil iodine.

of calculation.

hydrogenation agent, as does sulfur. Iodine reacts with highly unsaturated, conjugated olefinic or aromatic com pounds as shown by the results in Table I below. The ability of the compound to share itselectrons with iodine to form a complex seems to be a necessary prerequisite for having initial complexing action and subsequent carbon formation.

TABLE I Effect 0) Adding Iodine on the Coking Value of Aromatic Compounds After Heating at 475 C.

[10 gram samples used unless otherwise indicated] Coking Value. Percent by Weight Compound Without With With Iodine 10 p.p.h. p.p.h.

Iodine Iodine Acenaphthene 0. 2 11. 8 27. 2 Acenuphthylene- 40. 1 46. 8 52. 2 Acridine 8.7 9B. 4 Anthraccne 0. 3 25. 6 62. 9 2,3-Benzcdipheuylene 0xlde 0.1 6.0 Carbnzole 0.3 14. 7 Chrysene O. 2 1 33.6 1 34. 1 Fluoranthene.. 0. 1 2. 6 9. 7 Indene 1. 4 1 39. 6 41. 3 Naphthaceno 42. 8 l 85. 6 Phenanthrene. 0.3 6. 3 1 20. 4 0.1 10. 4 1 35. 4 O. 2 14. 1 0.5 6. 2 0.0 0.1 0.3 0. 1 0. 3 0. 5 0.0 0. 1 0.1 O. 1 0. 1 0.1 0.0 1. 8 2.6 Phenanthren 0. 3 6. 3 12.8

lndicates that samples weighing from 150 to 300 grams were used.

This is the preferred method What is claimed is:

l. A process for increasing the yield of carbon from aromatic compounds comprising forming a mixture of 1 to 30 parts of iodine with parts of an aromatic compound having a structure containing from two to four fused rings and capable of sharing electrons with iodine to form a complex therewith and coking said mixture under atmospheric pressure and collecting the thus-formed coke.

2. The process of claim 1, wherein said iodine is present in the range of 10 to 20 parts per one hundred parts of compound.

3. The process of claim 1, wherein said aromatic compound is selected from the group consisting of acenaph thene, anthracene, acridine, carbazole, chrysene, fiuoran thene, indene, phenanthrene, pyrene, quinoline, acenaphthylene, naphthacene, benzodiphenylene oxide, 1,2-benzanthracene, triphenylene, 3,4-benz-phenanthrene, alkyl derivatives thereof, and mixtures of aforesaid compounds.

4. A process for increasing the yield of carbon from aromatic compounds comprising forming a mixture containing from 1 to 30 parts by Weight of iodine to 100 parts by weight of an aromatic compound having a structure containing from two to four fused rings and capable of sharing electrons with iodine and heating said mixture in the absence of air first to a temperature below coking temperature at a rate of about 10 to about 60 per hour rise, holding said heated mixture at said temperature for several hours, and increasing said temperature to coking temperature until substantial coking of said compound has taken place.

5. A process for making graphite comprising forming a mixture containing aromatic compounds having from two to four fused rings and capable of sharing electrons with iodine and from about 1 to about 30 parts iodine per hundred parts of said aromatic compounds, coking said mixture under atmospheric pressure, and graphitizing the thus-produced coke.

6. A process for increasing the yield of carbon from indene, which process comprises forming a mixture of 1 to 30 parts iodine with 100 parts indene, coking said mixture under atmospheric pressure, and collecting the thus-formed coke.

References Cited in the file of this patent UNITED STATES PATENTS 1,984,164 Stock Dec. 11, 1934 2,246,645 Virbain et a1. June 24, 1941 2,915,370 Mitchell Dec. 1, 1959 2,960,554 Sandri et a1 Nov. 15, 1960 

1. A PROCESS FOR INCREASING THE YIELD OF CARBON FROM AROMATIC COMPOUNDS COMPRISING FORMING A MIXTURE OF 1 TO 30 PARTS OF IODINE WITH 100 PARTS OF AN AROMATIC COMPOUND HAVING A STRUCTURE CONTAINING FROM TWO TO FOUR FUSED RINGS AND CAPABLE OF SHARING ELECTRONS WITH IODINE TO FORM A COMPLEX THEREWITH AND COKING SAID MIXTURE UNDER ATMOSPHERIC PRESSURE AND COLLECTING THE THUS-FORMED COKE. 